The present invention relates to agricultural planters; and more particularly, it relates to planters for row crops. The two most important row crops in the United States are, of course, corn and soybeans in that order.
In an effort to increase crop yield, studies are continuously being made to determine the ideal spacing of crops--both the spacing of individual seeds in a row, and the spacing of adjacent rows. The present invention is directed primarily to problems associated with the spacing between adjacent rows as distinguished from intra-row spacing of individual plants.
By way of example, it was once popular to space rows of corn at 36 inches. Row spacing for hybrid corn now has generally been accepted to be best at about 30 inches. Soybeans, on the other hand, have a narrower row spacing. Current practice indicates a row spacing for beans of 15 inches, but this is determined to some extent by a desire to have the row spacing of corn a multiple of the row spacing for beans so that the same equipment can be set up and used for cultivating and harvesting.
Thus, from the standpoint of a manufacturer of agricultural planters, flexibility in permitting various row spacings is a very important consideration. Further, many farmers, particularly in the Corn Belt States of the United States plant both corn and beans. Some of these farmers, because of the short time normally available for good planting conditions, set up and use different planters for corn and for beans.
Another problem encountered by planter manufacturers is that their equipment will be used under different conditions of trash and seed bed preparation due to the various techniques employed by different farmers or in different regions for preparing the soil for planting. These techniques range from the conventional technique of moldboard plowing in the fall and additional tillage and seed bed preparation in the spring, to so-called "no-till" or minimum tillage planting in which a crop is planted on untilled soil or soil which is only slightly tilled. Problems arise in the no-till and minimum tillage practices because the planter must be capable of operating in conditions of high residue or "trash" as it is sometimes referred to. In other words, the planter must be capable of clearing trash and avoiding the accumulation trash during operation. This is a particularly accute problem for very narrow row spacings; and it has limited the use of popular row units employing double disk openers and adjacent gauge wheels on conventional planter frames for narrow row spacings because when the units are placed side-by-side on the same mounting bar, the gauge wheels of adjacent row units are so close together that they cannot adequately and reliably clear the trash in some instances. Thus, a second major problem with which a planter manufacturer must contend is the ability of the planter as a whole to operate satisfactorily and clear trash under the widely varying tillage and seed bed preparation practices employed and the current desire to achieve very narrow row spacings, such as for small seed crops where the desired row spacing is 71/2 to 10 inches.